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FirefoxWeb browser · Mozilla

CVE-2012-3960

HIGH · 10.0 CVSS v2.0 Published 2012-08-29
Fix available
A fix is available. Upgrade to 2.12 / 10.0.7 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Use-after-free vulnerability in the mozSpellChecker::SetCurrentDictionary function in Mozilla Firefox before 15.0, Firefox ESR 10.x before 10.0.7, Thunderbird before 15.0, Thunderbird ESR 10.x before 10.0.7, and SeaMonkey before 2.12 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via unspecified vectors.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Use-after-free vulnerability in mozSpellChecker::SetCurrentDictionary in Firefox, Thunderbird, and SeaMonkey allows remote attackers to execute arbitrary code or cause heap memory corruption. The vulnerability occurs when memory is freed but still accessed, potentially allowing controlled memory reallocation and code execution.

MitigationUpgrade to Firefox 15.0+, Firefox ESR 10.0.7+, Thunderbird 15.0+, Thunderbird ESR 10.0.7+, SeaMonkey 2.12+, or later patched versions to remediate this vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FirefoxWeb browser
Affected:< 15.0>= 10.0, < 10.0.7
Enterprise Linux DesktopOperating system
Affected:= 5.0= 6.0
Enterprise Linux EusOperating system
Affected:= 6.3
Enterprise Linux ServerOperating system
Affected:= 5.0= 6.0
Enterprise Linux Server EusOperating system
Affected:= 6.3
Enterprise Linux WorkstationOperating system
Affected:= 5.0= 6.0
Ubuntu LinuxOperating system
Affected:= 10.04= 11.04= 11.10= 12.04
SeamonkeyApplication
Affected:< 2.12

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:L/Au:N/C:C/I:C/A:C

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Firefox version
    Run 'firefox --version' or check the package manager (dpkg -l firefox, rpm -qi firefox)
    Affected if Version is < 10.0.7 OR >= 10.0 and < 15.0 (includes 10.x through 14.x)
  2. Check installed SeaMonkey version
    Run 'seamonkey --version' or check the package manager (dpkg -l seamonkey, rpm -qi seamonkey)
    Affected if Version is < 2.12
  3. Check installed Thunderbird version
    Run 'thunderbird --version' or check the package manager (dpkg -l thunderbird, rpm -qi thunderbird)
    Affected if Version is < 10.0.7 OR >= 10.0 and < 15.0 (includes 10.x through 14.x)
  4. Verify spell checker is enabled in the application
    In Firefox/Thunderbird/SeaMonkey, go to Preferences > Advanced > General > Check spelling, or inspect about:config for 'spellchecker.enable' setting
    Affected if Spell checking is enabled (value is true) - the vulnerability requires the spell checker component to be loaded and active
  5. Check OS version for Red Hat systems
    Run 'cat /etc/redhat-release' to identify the Red Hat Enterprise Linux version
    Affected if Version is exactly 5.0, 6.0, or 6.3 (these specific point releases are affected)

You are affected if you run Firefox < 10.0.7 or >= 10.0 with version < 15.0, SeaMonkey < 2.12, or the specific Red Hat/Ubuntu point releases listed, AND the spell checker component is enabled in the application.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.12 / 10.0.7 / 15.0 or later
Fixed in 2.1210.0.715.0
Interim mitigation

Upgrade to Firefox 15.0+, Firefox ESR 10.0.7+, Thunderbird 15.0+, Thunderbird ESR 10.0.7+, SeaMonkey 2.12+, or later patched versions to remediate this vulnerability.

Recommended fix High confidence

Firefox 15.0, Firefox ESR 10.0.7, SeaMonkey 2.12, or Thunderbird 15.0/ESR 10.0.7 depending on product in use

  1. Identify the affected application (Firefox, Firefox ESR, SeaMonkey, or Thunderbird) installed on the system
  2. For Red Hat Enterprise Linux systems: Run 'yum update firefox' or 'yum update seamonkey' to apply the security update
  3. For Ubuntu Linux systems: Run 'apt-get update && apt-get upgrade firefox' or 'apt-get upgrade seamonkey'
  4. For openSUSE systems: Run 'zypper update' to apply security patches
  5. After updating, verify the installed version matches the fixed release (Firefox 15.0, Firefox ESR 10.0.7, SeaMonkey 2.12, or Thunderbird 15.0/ESR 10.0.7)
  6. Restart the browser/application after updating to ensure the vulnerability is remediated
Caveat Upgrading to newer major releases may introduce compatibility issues with older extensions or plugins; test in a non-production environment first if possible

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2012-3960 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data